Beryllium Oxide Nanotubes and their Connection to the Flat Monolayer

Abstract

Single-walled zigzag beryllium oxide (BeO) nanotubes are simulated with an ab initio quantum chemical method. The (n,0) family is investigated in the range from n = 8 (32 atoms in the unit cell and tube radius R = 3.4 Å) to 64 (256 atoms in the cell and R = 27.1 Å). The trend toward the hexagonal monolayer (h-BeO) in the limit of large tube radius R is explored for a variety of properties: rolling energy, elastic modulus, piezoelectric constant, vibration frequencies, infrared (IR) intensities, oscillator strengths, and electronic and nuclear contributions to the polarizability tensor. Three sets of IRactive phonon bands are found in the spectrum. The first one lies in the 0−300 cm −1 frequency range and exhibits a very peculiar behavior: the vibration frequencies do tend regularly toward zero when R increases while their IR intensities do not; the nature of these normal modes is unveiled by establishing a connection between them and the elastic and piezoelectric constants of h-BeO. The second (680−730 cm −1 ) and third (1000−1200 cm −1 ) sets tend regularly, but with quite different slope, to the optical modes of the h-BeO layer. The vibrational contribution of these modes to the two components (parallel and perpendicular) of the polarizability tensor is also discussed. Simulations are performed using the CRYSTAL program which fully exploits the rich symmetry of this class of one-dimensional periodic systems: 4n symmetry operators for the general (n,0) tube.

Thermal properties of the orthorhombic CaSnO3 perovskite under pressure from ab initio quasi-harmonic calculations

“…Applications of this scheme cover a wide range of materials [76][77][78][79][80][81][82][83][84]. When a finite pre-stress σ pre is applied in the form of a hydrostatic pressure P , within the frame of finite Eulerian strain, the elastic stiffness constants become [85][86][87][88][89]:…”

Inducing a Finite In-Plane Piezoelectricity in Graphene with Low Concentration of Inversion Symmetry-Breaking Defects

“…We recently utilized the same approach for investigating the piezoelectric response of 3D systems such as SrTiO 3 , 35 BaTiO 3 , 43 Ge-doped quartz 44 and low-dimensional systems such as h-BN, 45 h-ZnO, 46 and BeO nanotubes. 47 Elastic constants and related properties are computed as strain numerical derivatives of analytical energy gradients. [48][49][50] …”

Ab initio simulations on migration paths of interstitial oxygen in corundum

“…[24], for periodic systems, which employs Gaussian-type functions (GTFs) centered on atomic nuclei as the basis sets (BSs). We have used the all-valence BS for atomic GTFs of oxygen (constructed using pure s-and d-as well as hybrid sp-AOs in the form of 6s-2111sp-1d as described elsewhere) [25] as well as the effective core pseudopotential (ECP) with 3s 2 3p 1 external shell developed for aluminum [26].…”